Extreme pressure lubricants containing dialkyl 1,2,2,2-tetrahaloethyl phosphates

ABSTRACT

Lubricating oils containing a small but effective amount of a dialkyl 1,2,2,2-tetrahaloethyl phosphate have been discovered to have excellent extreme pressure characteristics.

United States Patent Schneider et al.

[ Feb.8,.1972

[54] EXTREME PRESSURE LUBRICANTS CONTAINING DIALKYL 1,2,2,2- TETRAHALOETHYL PHOSPHATES [72] Inventors: John A. Schneider; John B. Moran, both of Midland, Mich.

[73] Assignee: The Dow Chemical Company, Midland,

Mich.

[22] Filed: July 24,1969

[21] Appl. No.: 844,661

[52] US. Cl ..252/49.9, 260/955, 260/963 [51] Int. Cl. ..C10m 1/46 [58] Field of Search ..252/49.9; 260/963 Primary Examiner-Daniel E. Wyman Assistant Examiner-W. Cannon Att0rneyGriswold & Burdick, Herbert D. Knudsen and D. H. Thurston [57] ABSTRACT Lubricating oils containing a small but effective amount of a dialkyl 1,2,2,2-tetrahaloethyl phosphate have been discovered to have excellent extreme pressure characteristics.

5 Claims, No Drawings EXTREME PRESSURE LUBRICANTS CONTAINING DIALKYL l,2,2,2-TETRAHALOETHYL PHOSPHATES BACKGROUND OF THE INVENTION Allen et al. in Journal of the American Chemical Society 78, 5 3715 (1956) and Ospenson et al., in US. Pat. No. 2,971,882 teach the preparation and use of a number of dialkyl tetrahaloethyl phosphates. The primary interest in these compounds to date has been their uses as multifunctional pesticides.

Knutson et al., in US. Pat. No. 2,340,33l teach that halogenated alkyl phosphates having halogen atoms on all alkyl groups such as tri-(B-chloroethyl)phosphate are useful as extreme pressure additives for lubricating oils. Although such compounds have been found to be effective, a continuing search has been made to discover compounds which are still more effective.

SUMMARY OF THE INVENTION According to the present invention, conventional lubricating oils containing a small but effective amount of a dialkyl l,2,2,2-tetrahaloethyl phosphate have excellent extreme pressure characteristics.

The dialkyl tetrahaloethyl phosphates of the present invention have the general formula X independently for each X a halogen.

Representative examples of such compounds include dimethyl l,2,2,2-tetrachloroethyl phosphate, diethyl l,2,2,2- tetrabromoethyl phosphate, dipropyl l,2-dichloro-2,2- dibromoethyl phosphate, diisopropyl l,2-difluoro-2,2- dichloroethyl phosphate, di-n-butyl l,2-dichloro-2,2-diiodoethyl phosphate, dinonyl l,2,2,2-tetrachloroethyl phosphate, methyl butyl l,2,2,2-tetrabromoethyl phosphate and n-propyl n-pentyl 1,2-dibromo-2,2-dichloroethyl phosphate. In the invention, those compounds wherein the alkyl groups contain from one to flve carbon atoms and wherein the halogens are chlorine or bromine are preferred, with dimethyl l,2-dibromo-2,2-dichloroethyl phosphate being especially preferred.

The tetrahaloethyl phosphate compounds of the present invention may be conveniently prepared by reacting a dialkyl 2,2-dihalovinyl phosphate with a free halogen or free interhalogen compound in the presence of an inert solvent and under photochemical catalysis. Although the reaction conditions of the addition may vary widely as different 2,2-dihalovinyl phosphates and different free halogens are employed in the reaction, the best results are generally obtained by maintaining the free halogen content in the reaction mixture relatively low and using reduced temperature. The catalytic effect of actinic radiation is usually required to give desirable yields when a free halogen is employed; however, the strength of the actinic radiation when an interhalogen compound such as bromine chloride is employed has been found to be immaterial.

The rate of addition of the free halogen in the preparation of the tetrahalo compound materially affects the yield and purity of the product compound. It has been found that whenever the amount of free halogen in the reaction mixture at any one time exceeds about 5 percent of the total halogen to be added, the purity of the reaction product is substantially decreased.

The conventional lubricating oils which contain the extreme pressure additives of the present invention may vary widely. Essentially any lubricating oil in which the extreme pressure additives of the present invention are compatible may be used. Generally, such lubricating oils are hydrocarbon-based fluids which contain in addition to the extreme pressure additive a number of other additives to improve various characteristics of the lubricating oil. Other lubricating fluids, however, such as Castor Oil and phenyl ethers may also be used.

The amount of the tetrahaloethyl phosphate contained in the lubricating oil of the present invention may vary as different lubricating oils are used, as different tetrahaloethyl phosphates are employed and as different extreme pressure characteristics are desired. Generally, desirable lubricating oils with good extreme pressure characteristics are obtained when such lubricating oils contain about 0.25 to about 5 percent or more by weight of the dialkyl l,2,2,2-tetrahaloethyl phosphate. Lubricating oils containing about 1 to about 3 percent by weight of the tetrahaloethyl phosphates are preferred. At higher concentrations, the phosphates of the invention may not be soluble and it may be necessary to add a small amount of a suitable solvent to solubilize the phosphate.

Using a lubricating oil containing a small but effective amount of a dialkyl l,2,2,2-tetrahaloethyl phosphate as described in the present invention, excellent extreme pressure lubricants are obtained. Such lubricating oils are useful for lubricating metal surfaces under high pressures such as those pressures encountered in modern high-performance engines where better lubrication than the lubrication afforded by conventional lubricants is required.

SPECIFIC EMBODIMENTS EXAMPLE 1 Preparation of Dimethyl l,2,2-Trichloro-2-Bromoethyl Phosphate To a mixture of 44.2 grams (0.2 mole) of dimethyl 1,1- dichlorovinyl phosphate, 11.7 grams (0.2 mole) of sodium chloride, 50 ml. of water and 50 ml. of methylene chloride was added 28 grams (0.24 mole) of bromine chloride with cooling and stirring. The bromine chloride was slowly added over 30 minutes, then the mixture was stirred for a few minutes at 25 C. and the layers were separated. After evaporation of the solvent from the methylene chloride layer, the residue was distilled at 117 C. and 0.5 mm. of Hg. The product was a colorless liquid which crystallized at 20 C. into an oily solid and was determined to be dimethyl l,2,2-trichloro-2- bromoethyl phosphate.

EXAMPLES 28 The effect of various compounds of the present invention was tested in a Shell Oil Company 4-Ball Extreme Pressure Tester. In such test the initial seizure load, the weight of load where the initial breakdown of lubrication begins, and the weld load, the weight of load at which the four balls cannot be rotated, are determined. The base fluid used in the test was a standard hydrocarbon lubricating oil containing 0.25 weight percent concentration of Ionol as an antioxidant. Various concentrations of the extreme pressure additives of the present invention were added to the base fluid and the improved extreme pressure characteristics are noted in Table 1. Example 2 is included for purposes of comparison between the base fluid and the fluids containing the extreme pressure additive of the invention.

3 Dimethyl l .Z-dibrorno-2,2-dichloroethyl phosphate l I20 500 4 L5 150 700+ 5 2 300+ 700+ 6 Dimethyl 1,21,2-

tetrachloroethyl phosphate l 110 300 7 2 I 300 8 Dirnethyl I ,2.2-trichloro- Z-bromuethyl phosphate 2 I00 400 In the same manner as described in the examples above, diethyl l,2,2,2-tetrabromoethyl phosphate, diisopropyl 1,2- difluoro-Z,Z-dichloroethyl phosphate, di-n-butyl 1,2-dichloro- 2,2-diiodoethyl phosphate and other phosphates of the invention may be used in the concentrations of the Examples in the lubricating oil above as extreme pressure additives.

Also, in the same manner, any of the extreme pressure additives of the invention above may be used in other lubricating compositions such as the various commercial brands of l0w40 oil and other such oils.

We claim:

1. An extreme pressure lubricant comprising a major amount of a conventional lubricating oil and a small but effective amount of a dialkyl l,2,2,2-tetrahaloethyl phosphate of III! the general formula O 1?: X ROIAIEOCIIE'ZX (I) X X R wherein R independently for each]! an alkyl of one to 10 carbon atoms X independently for each X a halogen.

2. The extreme pressure lubricant of claim 1 wherein each R is an alkyl group of one to five carbon atoms and each X is Cl or Br.

3. The extreme pressure lubricant of claim 1 wherein the dialkyl tetrahaloethyl phosphate is dimethyl l,2-dibromo-2,2- dichloroethyl phosphate.

4. The extreme pressure lubricant of claim 1 containing 0.25 to 5 percent by weight of the dialkyl tetrahaloethyl phosphate.

5. The extreme pressure lubricant of claim 4 containing 1 to 3 percent of the phosphate. 

2. The extreme pressure lubricant of claim 1 wherein each R is an alkyl group of one to five carbon atoms and each X is Cl or Br.
 3. The extreme pressure lubricant of claim 1 wherein the dialkyl tetrahaloethyl phosphate is dimethyl 1,2-dibromo-2,2-dichloroethyl phosphate.
 4. The extreme pressure lubricant of claim 1 containing 0.25 to 5 percent by weight of the dialkyl tetrahaloethyl phosphate.
 5. The extreme pressure lubricant of claim 4 containing 1 to 3 percent of the phosphate. 